1. Field of the Invention
The present invention relates to the field of optical scientific instrumentation. More specifically, the present invention relates to an optical instrument configured to perform emission (e.g., Raman and fluorescence) and transmission spectroscopy within the housing of the apparatus for identifying the chemical composition of a sample.
2. Discussion of the Related Art
Emission, e.g., Raman, and infrared (IR) transmission spectroscopy are complementary techniques capable of, if arranged appropriately, measuring the complete vibrational spectrum of a given sample. Presently, transmission and emission spectroscopy can be performed on standard optical instruments wherein, for example, the Fourier Transform Infrared (FT-IR) portion is primarily set up as a transmission instrument but because of space limitations within the sample compartment region, the emission spectroscopy portion (e.g., to include FT Raman) is often configured with the light source or sample arranged external to the housing of the instrument by way of one or more accessory units. Such resulting one or more accessories, however, can be quite bulky and require the user to move the sample from one sampling compartment to another to measure transmission and emission spectra of a single sample.
Background information on a system that overcomes sample compartment space limitations via accessories coupled external to the housing of the instrument, is described and claimed in, U.S. Pat. No. 5,499,095, entitled, “FOURIER SPECTROMETER WITH EXCHANGEABLE ENTRANCE AND EXIT PORTS ALLOWING FOR BOTH INTERNAL AND EXTERNAL RADIATION PORTS” issued Mar. 12, 1996, to Gast et al., including the following, “there are, however, a plurality of substances which cannot be prepared for a measurement with the assistance of these standard sample preparation measures. Included therein are gaseous samples, samples which must be cooled or heated, or samples whose dimensions are too large for the sample region. In order to spectroscopically measure samples of this kind it is necessary to utilize an appropriate accessory in or on which the sample can be arranged, and by means of which the measuring beam can be introduced onto the sample. Since, due to space limitations, such an accessory cannot be accommodated in the sample region of the spectrometer optics, it is necessary to position it outside of the spectrometer housing, whereby the measuring beam is guided out of the spectrometer optics.”
Background information on a combined infrared/Raman microscope system using moveable components but fixing the sample position, is described and claimed in, U.S. Pat. No. 5,841,139, entitled, “OPTICAL INSTRUMENT PROVIDING COMBINED INFRARED AND RAMEN ANALYSIS OF SAMPLES” issued Nov. 24, 1998, to Sostek et al., including the following, “the present invention provides the capability of performing microscopic infrared analysis and microscopic Raman spectroscopy on the same sample, on the same microscope, without removing the sample once it is set up for analysis.”
Accordingly, a need exists for an improved optical spectrometer, which can provide both transmission and emission (e.g., Raman and fluorescence) spectroscopy as provided by a single sample compartment configured to accept a more compact accessory within the confines of the housing. The present invention is directed to such a need.